Aquatic Ecology and Water Quality Management Group, Wageningen University & Research, P.O. Box 47, 6700 AA Wageningen, The Netherlands.
Food Chemistry Group, Wageningen University & Research, P.O. Box 17, 6700 AA Wageningen, The Netherlands.
Environ Sci Technol. 2023 Aug 8;57(31):11452-11464. doi: 10.1021/acs.est.3c02129. Epub 2023 Jul 28.
The transfer kinetics of plastic-associated chemicals during intestinal digestive processes is unknown. Here, we assessed whether digestive processes affect chemical exchange kinetics on microplastics, using an gut fluid digestive model mimicking the human upper intestinal tract. Chemical exchange kinetics of microplastics were measured for 10 polychlorinated biphenyls (PCBs) as proxies for the broad class of hydrophobic organic chemicals. Following earlier studies, olive oil was used as a proxy for digestible food, under high and low digestive enzyme activities. The micelle-water and oil-water partition coefficients of the 10 PCBs were also determined to evaluate the relative contribution of each gut component to sorb PCBs. A new biphasic and reversible chemical exchange model, which included the digestion process, fitted well to the empirical data. We demonstrate that the digestive processes that break down contaminated food can lead to a substantial increase in chemical concentration in microplastics by a factor of 10-20, thereby reducing the overall chemical bioavailability in the gastrointestinal tract when compared to a scenario without microplastics. Higher enzyme activities result in more chemicals being released by the digested food, thereby resulting in higher chemical concentrations in the microplastics. While the model-calibrated kinetic parameters are specific to the studied scenario, we argue that the mechanism of the reduced bioavailability of chemicals and the modeling tool developed have generic relevance. These digestive processes should be considered when assessing the risks of microplastics to humans and also biomagnification in aquatic food webs.
肠道消化过程中塑料相关化学物质的迁移动力学尚不清楚。在这里，我们评估了消化过程是否会影响微塑料上的化学交换动力学，使用一种模拟人体上消化道的肠道液消化模型。我们以 10 种多氯联苯（PCBs）作为疏水性有机化学品的代表，测量了微塑料的化学交换动力学。根据早期的研究，橄榄油被用作可消化食物的替代品，在高、低消化酶活性下进行实验。还测定了 10 种 PCBs 的胶束-水和油-水分配系数，以评估每个肠道成分对吸附 PCBs 的相对贡献。一个新的两相和可逆的化学交换模型，包括消化过程，很好地拟合了实验数据。我们证明，分解污染食物的消化过程会导致微塑料中化学浓度显著增加 10-20 倍，从而降低胃肠道中化学物质的总体生物利用度，与没有微塑料的情况相比。更高的酶活性会导致更多的化学物质从消化的食物中释放出来，从而导致微塑料中更高的化学浓度。虽然模型校准的动力学参数特定于所研究的情况，但我们认为，化学物质生物利用度降低的机制和开发的建模工具具有普遍意义。在评估微塑料对人类的风险以及水生食物网中的生物放大时，应考虑这些消化过程。
